(a) Field of the Invention
The present invention relates to a transmitting apparatus and a retransmitting method. More particularly, the present invention relates to an automatic repeat request (ARQ) retransmitting method.
(b) Description of the Related Art
A wireless communication system generally uses a method of retransmitting a packet that fails in transmission, and an ARQ method is used as a retransmission method. In a conventional ARQ method, a protocol data unit (PDU) is formed by fragmenting a service data unit (SDU) into an ARQ block, and continuous sequence numbers are allocated to the fragmented ARQ blocks. A sequence number of the first ARQ block of ARQ blocks belonging to each PDU is indicated to each PDU such that each PDU can be reassembled at the receive side.
A method of retransmitting a PDU includes a method of rearranging and transmitting the PDU and a method of not rearranging the PDU and transmitting the PDU that fails in transmission. When rearranging and transmitting a PDU, ARQ blocks that are included in the PDU to retransmit are divided into several PDUs and transmitted.
In this case, because the size of an ARQ block that is used for initial transmission and retransmission is fixed, this method may not appropriately correspond to a wireless environment. For example, when transmission of an ARQ block having a size of 100 bytes has failed, it can increase success probability of transmission to transmit an ARQ block of a somewhat small size. However, when the size of an ARQ block to be retransmitted is limited by a predetermined size, it is difficult to increase transmission success probability.